Because they are so vast in number, catching mosquitoes isn’t an easy (or cheap) task. In Singapore, the National Environment Agency has come up with one low-cost means of stopping mosquitoes – Gravitraps.

These cylinders, containing hay-infused water, attract female Aedes aegypti mosquitoes searching for a place to lay their eggs. If the mosquito lays eggs before getting caught in sticky tape, then a barrier of wire mesh prevents any hatchlings making it into the outside world.

The challenge – as outlined by The American Journal of Tropical Medicine and Hygiene in their 2013 study – is setting the right number of Gravitraps in the right place at the right time. The scientists placed Gravitraps in mid-rise apartment blocks in 11 dengue cluster areas in Singapore. Investigators checked them over a 16-week period, and Aedes aegypti mosquitoes were caught in all but one of the clusters. To be effective, they recommend that a large number of Gravitraps, at least five per apartment block, be deployed.

Being an inexpensive option for public health boards is an upside of the Gravitraps, according to the researchers. And results from trials in Singapore have been positive: they’ve been rolled out across housing estates earlier this year, and in construction sites – as featured on the news in March 2014.